AIRMONITORING 21


Luke does recall one occasion when the accuracy of a Vaisala CO2 sensor was called into question. An installed probe was providing


readings that were abnormally low, so a site visit was necessary. However, such was their faith in the sensors that an alternative explanation was sought, and after a period of speculation a Google search solved the mystery by revealing the propensity of (nearby) curing concrete to absorb CO2


as carbonation.


Advanced sensor technology The Vaisala CARBOCAP®


Carbon Dioxide Probe GMP252 is an


intelligent carbon dioxide sensor designed for harsh and humid environments where stable and accurate CO2


measurements


and New Zealand. We have also utilised Vaisala humidity and temperature sensors in a variety of similar applications. In comparison with some other CO2


are required. Importantly, the probe features second generation CARBOCAP®


technology. In addition to measuring CO2 sensors, the Vaisala monitors


were more expensive, but they were very popular with our contractors and we found that Vaisala’s product reliability lowered the cost of ownership.”


Luke Breeuwer agrees with Shannon on the longer term benefits of investing in higher quality instruments, adding: “The MODBUS communications capability of the Vaisala Indigo200 Transmitter with the GMP252 probe is also a major advantage for us; it means that the amount of wiring required is substantially reduced, which lowers both complexity and costs.”


Commenting on the reliability of the Vaisala probes, Luke says: “We have large numbers of these sensors in operation but there have been no breakdowns or urgent call-outs, so the ongoing costs have been negligible. We are required to check sensor calibration every two years, but they are so stable that this check always shows the sensors to be within specification, which is great.”


, an


electrically tunable micromechanical filter enables a reference measurement at a wavelength where no absorption occurs. The reference measurement compensates for any potential changes in the light source intensity, as well as for contamination in the optical path, which means that the sensor is extremely stable over time. The probe also automatically compensates for temperature, pressure, oxygen and humidity, and with an operating temperature range from -40 to +60 °C, the sensor is able to measure CO2


ppm with reduced accuracy.


Benefits of the Vaisala technology From Woolworths’ perspective Luke says: “The main advantages are reliability, low maintenance and MODBUS communications. However, flexibility is important because we also utilise the Vaisala probes in-store to ensure that CO2


levels do not rise excessively.


We achieve this by using monitoring data to automatically control and optimise fresh air intake.”


Looking forward By identifying the role of natural refrigerants in its Corporate Responsibility Strategy, Woolworths has made a very clear statement of intent. Two years ago, there were no transcritical CO2


Summarising Luke says: “By utilising CO2 in our refrigeration


systems we are helping to lower greenhouse gas emissions whilst also lowering operational costs. However, reliable CO2


monitoring


plays a vitally important role; protecting staff and the public, while helping to identify and reduce leakage – a win win situation!”


All photos: Courtesy of Woolworths, Australia accurately from 0 to 10,000 ppm, and up to 30,000


Vaisala is a global leader in weather, environmental and industrial measurements. Building on over 80 years of experience, Vaisala provides observations for a better world. We are a reliable partner for customers around the world, offering a comprehensive range of innovative observation and measurement products and services. Headquartered in Finland, Vaisala employs approximately 1,850 professionals worldwide and is listed on the Nasdaq Helsinki stock exchange.


through a process known


Emerson integrates the probes within its building management systems and Shannon highlights the facility to utilise a dual relay output for local alarms as a particularly useful feature. “Reliability is of course the main advantage for us,” he adds. “But the negligible maintenance requirement, the two year calibration check and MODBUS comms provide us with competitive advantages.”


stores in the group, but seven stores have now been converted and up to a dozen largely metropolitan stores will be converted in the coming year.


Contact Details Anthony Ulrich, Vaisala • Vaisala Pty Ltd, 3 Guest Street, Hawthorn, VIC 3122, Australia • Tel + (61 3) 9815 6700 • Email: anthony.ulrich@vaisala.com • Web: www.vaisala.com


New optical spectrum analyser unlocks new possibilities for environmental sensing and medical applications


For environmental sensing applications, lasers are increasingly being used to detect gases such as CO2


, N2


the wavelength absorption lines of the different gases. However, the side modes of the laser, which are normally hard to detect, reduce the laser’s capability to distinguish between the various gases.


In the 3.5 to 5µm range (mid infrared) the AQ6377, from Yokogawa, is the only OSA that is capable of analysing the wavelength spectrum of lasers, including their side modes, with high accuracy.


Gas sensor system manufacturers will now be able to evaluate the purity of the emissions and to characterise the lasers more precisely, thus enabling the selection of the best laser(s) for specific applications.


Quantum Cascade Lasers (QCL), which are increasingly being used for medical spectroscopy diagnostics, operate using a pulsed technique, across a very wide wavelength range. Yokogawa’s AQ6377 is now able to offer the capability to perform stable measurements in this wide wavelength range and also to evaluate pulsed QCL signals with low repetition rates, which has hitherto been difficult to achieve. The AQ6377 therefore delivers a true step change, allowing researchers to work with various pulse lengths and repetition rates.


Key features of the AQ6377, which together provide the capability to visualise the side-modes of MWIR lasers, include a wavelength resolution of 0.2 nm, a wavelength accuracy of ±0.5 nm, a high dynamic range of 50 dB, and a level sensitivity down to -60 dBm. The wide dynamic range and high sensitivity have been achieved by reducing the influence of stray-light in the monochromator. The built-in calibration light source takes advantage of the natural absorption properties of acetylene gas to deliver a wavelength calibration signal which is accurate to 0.6 picometres. This source is also used in conjunction with the automatic optical alignment capability to compensate for any deviation in the optical axis caused by vibrations and shock suffered in transit, and those due to temperature changes. Using those features, the AQ6377 can maintain its high optical performance on site.


In addition, the free-space optical input makes it possible to connect both single-mode MWIR fibres and multimode (up to 400 µm) to the same instrument, and delivers a low and stable insertion loss, which increases measurement repeatability. The lack of physical contact also eliminates the possibility of damage when fibres are connected.


Another important feature of AQ6377 is purging. In the MWIR region, spectral measurements can be strongly influenced by the absorption of water vapour and carbon dioxide. The purging feature is designed to significantly reduce the influence of these gases by continuously supplying a pure purge gas, such as nitrogen, to the monochromator through the dedicated connectors on the back panel.


“With the global attention to air quality and the effects of greenhouse gases, we take pride in our ability to help improve the accuracy of their measurements.”, says Terry Marrinan, VP Sales & Marketing Yokogawa Europe and South-East Asia: “By creating the AQ6377 high performance OSA, we are responding to the needs of customers developing solutions for optical gas sensing as well as surgical equipment who require measurement equipment of a maximum performance that is also easy-to-use and maintain.”


For More Info, email: email:


For More Info, email: 51257pr@reply-direct.com WWW.ENVIROTECH-ONLINE.COM AET ANNUAL BUYERS’ GUIDE 2020


For More Info, email: email:


O and NO. They achieve this by identifying


High performance yet economic GC for trace level environmental monitoring


ENMET’s eGC (environmental Gas Chromatograph) is a fully autonomous trace toxic chemical fenceline monitor for field applications capable of subparts per billion analysis. A typical application for the eGC can be single or multi chemical identification of specific hydrocarbons such as Benzene, Toluene, and Xylene in ambient air. The eGC is designed to be an autonomous field instrument capable of operating while using only solar power allowing mobility convenience of deployment to specific emission and remote site areas. eGC has been tested to operate outdoors under harsh conditions with ambient temperature range of 14°F to 115°F. This system will last years in the field with minimal planned maintenance limiting user field interaction. The eGC reports all of the analysis data including weather wind speed and direction with GIS position. All data is sent by cellular modem using an encrypted server, secure, with full access to the data anywhere in the world via the web. ENMET’s eGC is a significant technological improvement for trace level field analysis offering high performance at a very affordable price.


For More Info, email: email:


50990pr@reply-direct.com


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